But as these signals cross interstellar medium, they would become very diffuse and difficult to focus at the receiving end.
"There are two things that you would need to get such a signal-firstly, it has to be able to leave our planet, secondly it would have to have as much power as possible," Davis noted. "As you go into space that power would dissipate. They would need more and more sensitive equipment to pick it up."
I'm sure that if advanced civilizations exist, they will have the ability to detect Earth's faintest television-radio signals. Of the question, what would aliens make of these signals, well, that's anybody's guess.
But, somewhere-out there-the television broadcasts of the Apollo 11 lunar landing, and original episodes of "Star Trek" and "The Brady Bunch" are approaching the recently discovered planetary system of Zeta Reticuli.
Farther out into space, the original broadcast signals of "The Lone Ranger" and "Howdy Doody" are approaching the planets orbiting Pi Mensae.
And reaching even farther into the vastness of of the Milky Way, hypothetical extraterrestrials 73 light years distant may be watching humanity's first interstellar greeting-from none other than Adolph Hitler.
What's in the Sky: Look for beautiful star cluster M34 visible in binoculars in the constellation Perseus, in the northwest, this weekend before sunrise. The star Mirphak (also Mirfak) is Perseus' brightest object.
Lou Varricchio, M.Sc., is a former NASA science writer. He is a NASA-JPL Solar System Ambassador in Vermont and the 2009 recipient of U.S. Civil Air Patrol-USAF auxiliary's Maj. Gen. Chuck Yeager Aerospace Education Achievement Award.